Index: bp-templates/bp-legacy/buddypress-functions.php
===================================================================
--- bp-templates/bp-legacy/buddypress-functions.php
+++ bp-templates/bp-legacy/buddypress-functions.php
@@ -126,6 +126,12 @@ class BP_Legacy extends BP_Theme_Compat {
 
 		}
 
+		/** Notices ***********************************************************/
+
+		if ( bp_is_active( 'messages' ) ) {
+			add_action( 'wp_footer', array( $this, 'sitewide_notices' ), 9999 );
+		}
+
 		/** Ajax **************************************************************/
 
 		$actions = array(
@@ -293,7 +299,26 @@ class BP_Legacy extends BP_Theme_Compat {
 	 * @since BuddyPress (1.7)
 	 */
 	public function localize_scripts() {
+	}
+
+	/**
+	 * Outputs sitewide notices markup in the footer.
+	 *
+	 * @since BuddyPress (1.7)
+	 *
+	 * @see https://buddypress.trac.wordpress.org/ticket/4802
+	 */
+	public function sitewide_notices() {
+		// Do not show notices if user is not logged in
+		if ( ! is_user_logged_in() )
+			return;
+
+		// add a class to determine if the admin bar is on or not
+		$class = did_action( 'admin_bar_menu' ) ? 'admin-bar-on' : 'admin-bar-off';
 
+		echo '<div id="sitewide-notice" class="' . $class . '">';
+		bp_message_get_notices();
+		echo '</div>';
 	}
 
 	/**
Index: bp-templates/bp-legacy/css/buddypress.css
===================================================================
--- bp-templates/bp-legacy/css/buddypress.css
+++ bp-templates/bp-legacy/css/buddypress.css
@@ -506,7 +506,8 @@ body.activity-permalink #buddypress div.activity-comments div.acomment-content {
 #buddypress div#message.updated {
 	clear: both;
 }
-#buddypress div#message p {
+#buddypress div#message p,
+#sitewide-notice p {
 	font-size: 90%;
 	display: block;
 	padding: 10px 15px;
@@ -545,7 +546,20 @@ body.activity-permalink #buddypress div.activity-comments div.acomment-content {
 #buddypress ul.button-nav li.current a {
 	font-weight: bold;
 }
-
+#sitewide-notice #message {
+	left: 2%;
+	position: fixed;
+	top: 1em;
+	width: 96%;
+	z-index: 9999;
+}
+#sitewide-notice.admin-bar-on #message {
+	top: 3.3em;
+}
+#sitewide-notice strong {
+	display: block;
+	margin-bottom: -1em;
+}
 
 /*--------------------------------------------------------------
 6.5 - Forms
@@ -1004,7 +1018,8 @@ a.bp-title-button {
 	font-weight: bold;
 }
 #buddypress span.activity,
-#buddypress div#message p {
+#buddypress div#message p,
+#sitewide-notice p {
 	border: 1px solid #e1ca82;
 	-moz-border-radius: 3px;
 	-webkit-border-radius: 3px;